When a plurality of like first connectors and like second connectors matable therewith are used in the same vicinity, it is important to provide means to permit mating of particular pairs intended to be mated to each other, while preventing mating of pairs not intended to be mated to each other. This may be accomplished by use of visual coding such as indicia, but is much preferred to be accomplished by keying mechanisms which physically prevent mating of connectors not intended to be mated to each other while allowing desired mating of appropriate pairs. In one manner of keying, key members are known which are secured in one of the first and second connectors which cooperate with opposing key members of the other. Each key member is secured in a selected orientation with respect to its opposing key member so that forward structure or both pass by each other during mating; if another like connector is used in place of one of them, with its key member oriented differently, the forward structure of the opposing key members will abut and prevent further axially forward movement and thereby prevent mating. Orientation of a key member in a connector can be accomplished by using a member of regular polygonal cross-section secured in a passageway of like cross-section, with the number of sides of the polygon determining the number of orientations available from which to select. Using a pair of key members increases the number of keying arrangements to equal the square of the number of sides of the polygon.
It is desired to retain a pair of key members at ends of elongate narrow module housings without additional fastening members.
It is further desirable to retain a key member in a housing in a manner facilitating removal thereof.
It is further desirable to retain a key member in a housing passageway in a manner not permitting rotational movement, nor axial movement or axial misalignment.
It is also desirable to provide retention means for an insert in a housing passageway including a projection moldable along one side of the passageway which can retain the insert in any angular orientation in the passageway against rotational movement, axial movement and axial misalignment.